The real Death Note story is quite complex. Light Yagami discovers the Death Note and begins his crusade against criminals. He quickly becomes a sort of self - appointed judge, jury, and executioner. As he kills more and more people, his sense of morality becomes warped. L enters the picture and starts his investigation. L is a very unique character, with his odd habits like sitting in a crouched position. Their struggle is not just a physical one but also a mental and moral one. Light has to constantly come up with new ways to avoid detection by L, and L has to find ways to prove that Light is the one using the Death Note. It's a story full of suspense, moral dilemmas, and psychological battles.
Overall, the Death Note Christmas comic could be a festive spin-off that maintains the dark and mysterious tone of the original series while adding holiday elements. It might explore new aspects of the characters' interactions during the Christmas season.
Ryuk would probably just be amused. He is a Shinigami who has seen a lot in his existence. Fanfiction is just another strange human creation to him. He might chuckle at some of the more outlandish ideas in the fanfictions, like a character having superpowers beyond the Death Note.
It was mainly inspired by the creator's imagination. The concept of having power over life and death in such a unique way makes for a very interesting and dark story idea.